"For being able to do password resets later" - don't need to validate. Mailing list - reluctant OK "avoiding sending private info to the wrong user" - how cou

"For being able to do password resets later" - don't need to validate. Mailing list - reluctant OK "avoiding sending private info to the wrong user" - how could this happen? "avoiding allowing someone to masquerading or impersonate someone they're not" - how could this happen? Like if I signed up as tim@apple.com? What could realistically happen?